Impact damping arrangements are generally used for damping motor vehicular impact and are connected on the one hand on the cross member which is connected to the bumper and on the other hand to the vehicle frame. In the event of a collision which impacts externally on the bumper, the device prevents greater damage being caused to the frame of the vehicle. The cross member and the vehicle frame are designed with a high degree of rigidity so that the energy from a relatively minor collision is not absorbed by a plastic deformation in the cross member nor in the vehicle frame. This is achieved in that the impact damping arrangement absorbs the impact energy, thereby greatly reducing the forces acting on the vehicle frame. Damage to the panel components of the vehicle frame can thus be avoided, which greatly reduces or avoids possible repair costs. The impact damping arrangement is usually configured such that it absorbs the impact energy by a partial plastic deformation, so that when the vehicle is repaired, it is only the impact damping arrangement itself which has to be replaced.
DE 200 13 385 U1 discloses an impact damping arrangement of this type for motor vehicles. This impact damping arrangement for motor vehicles has a damper with a deformation tube which has at least one longitudinal slot extending in an insertion direction and a recess formed at one end of the longitudinal slot, the diameter of which is greater than the width of the longitudinal slot. In the event of an impact, the deformation tube is driven in the insertion direction through a supporting tube surrounding the deformation tube in the direction of the vehicle frame, deformation portions widening longitudinal slots which extend along the wall of the deformation tube, with a corresponding irreversible deformation of the deformation tube. As a result of the arrangement of the impact damping arrangement in the longitudinal direction of the vehicle and in particular due to the longitudinal slots configured along the deformation tube, the energy absorption of an impact is possible only in the longitudinal direction of the vehicle, so that impact forces which act transversely or at an angle to the vehicle cannot be absorbed by the impact damping unit. In the event of a transverse impact, this can result in considerable damage to the vehicle frame, which can mean that complex and thus costly repairs are necessary.
DE 198 32 114 A1 discloses an impact damper for motor vehicles which has an outer supporting tube and a deformation tube which is displaceable therein. Furthermore, a reversible impact damper is provided with a displaceable cylindrical housing projecting over the free end of the supporting tube and a piston rod which is guided displaceably in a reversible damped manner in the housing and which is connected to the deformation tube at least in the insertion direction. A deformation device is also provided with a reinforced projection configured on the supporting tube and protruding towards the axle. The impact damper is characterised in that the free end of the deformation tube projects with a guide portion over the free end of the supporting tube counter to the insertion direction and the housing is guided displaceably in the guide portion.
The known impact damping arrangements encounter the problem that due to the guidance and to the tubes which run one inside the other as supporting tube and deformation tube, it is only possible for an impact in the longitudinal direction of the impact damper to be absorbed, so that forces which arise transversely to the impact damper are introduced into the vehicle frame without being reduced. The impact dampers are attached by welds which have a high degree of rigidity and in the event of a force acting transversely at an angle to the longitudinal axis of the tubes, the welds can cause considerable damage to the vehicle frame due to their low flexibility. Thus, flexibility is provided only in the longitudinal direction of the damping unit, and force effects arising at an angle to the longitudinal axis cannot be absorbed.
It is known from the familiar rear AZT crash repair test, new RCAR structural test—10°, Allianz Zentrum für Technik GmbH, that to classify possible damage to a vehicle frame, impact tests are usual in which a collision is produced between a barrier (1000 kg-1400 kg) with a movement (15+1 km/h) at an angle (10°) to the longitudinal axis of the vehicle and the motor vehicle with a partial overlap (40%). As a result, a new loading condition is produced for the impact damping arrangement which has a transverse component of the acting force based on the longitudinal axis of the vehicle. However, this transverse force component cannot be absorbed by present impact damping arrangements without the possibility of the vehicle frame being damaged.
It is therefore the object of the present invention to provide an impact damping arrangement which absorbs an impact in the longitudinal direction of the motor vehicle as well as an impact with a force effect which runs transversely to the longitudinal axis of the motor vehicle.